Transistor-relay pulse generator



Sept. 28, 1965 w. L. DEEG TRANSISTOR-RELAY PULSE GENERATOR Filed May 12, 1961 R W mm M N5 Y M mw WA 2 W N m m An V, W

BY W W 3,209,175 TRANSlTOR-RELAY PULSE GENERATOR Wyman L. Deeg, Glenview, 11L, assiguor to C. P. Clare & Company, Chicago, 111., a corporation of Delaware Filed May 12, 1961, er. No. 109,543 8 Claims. (Cl. 307132) This invention relates to a signal generator and, more particularly, to a new and improved pulse generator including transistor driven relay means.

Many different types of systems used, for instance, in the fields of industrial control, communications, and data handling require one or more pulse generators. In many applications, the generators are used as timing pulse sources that require accurate frequency control and, in other applications, the generators provide sources of driving pulses and should be capable of delivering an appreciable amount of power. The generators should also be capable of being easily and economically fabricated and should not require excessive installation space.

Accordingly, one object of the present invention is to provide a new and improved pulse generator.

Another object is to provide a pulse generator including new and improved circuit means for controlling the operation of an output relay.

A further object is to provide a pulse generator comprising a sealed switch unit driven by one or more transistors in which the sealed switch unit includes a single set of contacts that both provides an output signal and controls the operation of the transistor.

Another object is to provide a pulse generator including a single relay driven under the control of a pair of transistors in which a single set of contacts not only provides an output signal, but also positively synchronizes the operation of the transistors and controls the application of control or biasing potentials thereto.

In accordance with these and many other objects, an embodiment of the invention comprises a relay having an operating winding that is connected in series with the emitter-collector circuit of a first transistor across a potential source. The base electrode of this first transistor is connected to a timing capacitor that is connected across the potential source through an adjustable charging resistor and a pair of normally closed contacts on the relay. These contacts also form a part of a voltage dividing network by which the emitter of the first transistor and the emitter of a second transistor that is connected in parallel with the timing capacitor are provided with a biasing potential. When the capacitor is charged to the point at which the first transistor is rendered conductive, the relay is operated to open the normally closed contacts and to close a single pair of normally open contacts.

The opening of the first contact interrupts the charging circuit for the capacitor, which begins to discharge through the conductive first transistor, and also changes the bias supplied to the emitters of the tWo transistors. The closure of the second pair of contacts operates an output relay and applies a potential to the base electrode of the second transistor so that this transistor conducts to provide an additional controlled discharge path for the timing capacitor. When the capacitor has been suitably dis charged, the first transistor is rendered non-conductive to release the relay so that the second relay is released and the second transistor is rendered nonconductive.

By controlling the magnitude of the resistance in the charging circuit for the timing capacitor, the released period of the relay is controlled. By varying the magnitude of the potential applied to the second transistor, the eiTective collector impedance of the second transistor is controlled to select the period required to discharge the timing capacitor. This adjusts the period during which the 3,239,175 Patented Sept. 28, 1965 relay is maintained in an operated condition. Since the contacts of the relay form a part of the feedback pathincluding the second transistor, the relay is positively held in phase with the first transistor to insure accurately timed output signals. Since only a single set of make and break contacts are required in the pulse generator, the relay can comprise a sealed mercury relay that is both sensitive and capable of supplying substantial power over extended periods of operation.

Many other objects and advantages of the invention will ecome apparent from considering the following detailed description in conjunction with the single sheet of drawings which provides a schematic circuit diagram of a pulse generator embodying the present invention.

Referring now more specifically to the drawing, therein is illustrated a pulse generator, indicated generally as 10, which includes a pair of transistors 12 and 14 for controlling the operation of a relay indicated generally as 16. When the transistor 14 is rendered conductive, the relay 16 is operated to energize an output relay 18 and to render the transistor 12 conductive. When the transistor 12 is rendered conductive, the transistor 14- is rendered nonconductive to release the relays 16 and 18 and to render the transistor 12 nonconductive.

The relay 16 includes an operating winding 20 for selectively actuating a pair of normally closed contacts 22 and a pair of normally open contacts 24. The operating winding 29 is connected in series with a resistance element 26 and the emitter-collector path of the transistor 14, and this circuit is connected across a suitable potential source, such as a battery 28. To provide means for controlling the transistor 14, a timing capacitor 30 is connected between the positive terminal of the battery 28 and the base electrode of the transistor 14 and this terminal of the capacitor 30 is also connected to the negative terminal of the battery 23 through an adjustable resistor or potentiometer 32 and the normally closed contacts 22 on the relay 16.

The emitter electrodes of the transistors 12 and 14 are provided with a biasing potential by a voltage dividing network including the resistance element 26 and a plurality of additional resistance elements 34, 36, and 38 that are connected across the battery 28. This voltage dividing network also includes a path that is connected in parallel with the resistance element 34 when the relay 16 is released. This parallel path includes the normally closed contacts 22, a resistance element 40, and a diode 42. In one generator 19 constructed in accordance with the present invention, the voltage dividing network supplies the emitter of the transistor 14 with a potential that is approximately eighty percent of the voltage of the battery 28.

When the capacitor 30 is charged over the circuit including the closed contacts 22 and the potentiometer 32 to a point at which the base of the transistor 14 becomes slightly negative with respect to its emitter, the transistor 14 is rendered conductive so that the winding 20 of the relay is energized. This operates the relay 16 to open the contacts 22 and to close the contacts 24. The opening of the contacts 22 interrupts the charging circuit for the capacitor 30 so that the capacitor 30 begins to discharge through the conductive transistor 14. The diode 42 is now biased in a reverse direction so that the capacitor 30 cannot be charged from the battery 28 over the path including the series connected resistances 34, 40 and 32. The opening of the contacts 22 removes the resistance element 40 from the voltage dividing network connected to the emitter electrodes of the transistors 12 and 14 to reduce the potential applied to the emitters. In a pulse generator 10 constructed in accordance with the present invention, the removal of the resistance element J 40 from the voltage dividing network places the emitter of the transistor 14 at approximately fifty percent of the potential of the battery 28.

The closure of the contacts 24 provides an output signal and, in the pulse generator shown in the draw ings, is used to control the operation of the slave output relay 18. This relay includes an operating winding 44 which is shunted by a diode 46 and which is connected in series with the battery 28 through the closed contacts 24. When the winding 44 is energized, a pair of normally closed contacts 48 are opened and a pair of normally open contacts 50 are closed. The contacts 48 and 50 can be connected to a suitable load device, although this load device could be connected directly to the contacts 24.

The closure of the contacts 24 also completes a circuit for controlling the time period that the transistor 14 remains-in a conductive condition. More specifically, when the contacts 24 are closed, the battery 28 is connected in series with a voltage dividing network including a resistance element 52, a potentiometer 54 and an additional resistance element 56 that is also connected to the base electrode of the transistor 12. The potential provided by this network biases the base of the transistor 12 negative with respect to its emitter electrode so that this transistor conducts to provide a discharge path for the timing capacitor 30. By varying the setting of the potentiometer 54, the effective collector impedance of the transistor 12 is vanied to control the time required to discharge the capacitor 30.

When the capacitor has discharged to the point at which the base electrode of the transistor 14 is no longer negative with respect to its emitter electrode, the transistor 14 is rendered nonconductive so that the relay 16 releases to close the contacts 22 and to open the contacts 24. The opening of the contacts 24 releases the relay 18 and renders the transistor 12 nonconductive to remove the low impedance shunt or discharging path connected in parallel with the timing capacitor 30. The

closure of the contacts 22 increases the bias supplied to the emitter electrodes of the transistors 12 and 14 and completes the charging path for the timing capacitor 30. The potentiometer 32 is efiective to control the interval required to charge the capacitor 30 to the value at which the base of the transistor 14 again becomes negative with respect to its emitter electrode. Thus, the potentiometer 32 controls the period during which the relay 16 is maintained in a released or inoperative condition. When the transistor 14 is again rendered conductive, the relays 16 and 18 are operated in the manner described above.

Accordingly, the pulse generator 10 includes means for accurately controlling the operation of the relay 16 and provides a pulse generator in which the inclusion of the contacts 22, 24 controlled by this relay in the feedback path including the transistor 12 positively synchronizes the operation of relay 16 with the driving transistor 14. Further, since the pulse generator 10 requires a relay having only a single pair of break contacts 22 and a single pair of make contacts 24, the relay 16 can comprise a sealed mercury switch capsule that is both sensitive and capable of supplying a substantial power output over a virtually unlimited life span.

In one pulse generator 10 constructed in accordance with the present invention, the relay 16 comprised a sealed mercury switch manufactured by C. P. Clare & Company of Chicago, Illinois and identified as type HGS-lOOS. The slave relay 18 used with the relay 16 comprised a type HG-lOOZ relay also manufactured by C. P. Clare & Company. In this representative pulse generator 10, the circuit components had the values listed ,7

Capacitor 30 8 afd. Resistors 36, 52 and 56 10 K. Resistors 26, 34 and 38 1 K. Resistor 40 270 ohms. Potentiometer 32 K. Potentiometer 54 500 K. Transistors 12 and 14 2N1373. Diodes 42 and 46 1N1763.

Although the present invention has been described with reference to a single embodiment thereof, it will be understood that those skilled in the art can make many other modifications and embodiments that will fall within the spirit and scope of the principles of this invention.

-What is claimed and desired to be secured by Letters Patent in the United States is:

1. A pulse generator comprising relay means includ ing an operating winding and two pairs of contacts, one of said pairs of contacts being normally open and the other of said pairs of contacts being normally closed; a first controlled conduction device having a control electrode and being connected to said operating winding to control the operation of said relay means; capacitive means connected to said control electrode; a second controlled conduction device connected to said capacitive means; a potential source; and circuit means including a first pair of said contacts for connecting said potential source to said capacitive means to charge said capacitive means, sald circuit means also including a second pair of said contacts for connecting said potential source to said second controlled conduction device to control the discharge of said capacitive means.

2. The pulse generator set forth in claim 1 including output means connected to said potential source through said second pair of contacts.

3. The pulse generator set forth in claim 1 in Which said first controlled conduction device includes a second control electrode and in which said circuit means includes means controlled by said first pair of contacts-for applying potentials of different magnitudes to the second control electrode of said first controlled conduction device.

4. A signal generator comprising relay means including two pairs of contacts, one of said pairs of contacts being normally open and the other of said pairs of contacts being normally closed, a first controlled conduction device having two control electrodes and an output electrode, means connecting said output electrode to said relay means to provide means for operating and releasing said relay means, capacitive means connected to one of said control electrodes, a potential source, means including a first one of said pairs of contacts for connecting both of said control electrodes to said potential source, a second controlled conduction device having a control electrode and being connected to said capacitive means, and means including a second one of said pairs of contacts for connecting said potential source to the control electrode of said second controlled conduction device.

5. A pulse generator comprising relay means having an operating winding and contact means controlled thereby, a first transistor having a base electrode, a potential source, means connecting said winding and said first transistor in series across said potential source, capacitive means connected to the base electrode of said first transistor, first circuit means including said contact means for connecting said capacitive means across said potential source to provide a charging circuit for said capacitive means, a second transistor having a base electrode, means connecting said second transistor in parallel with said capacitive means, and second circuit means including said contact means for connecting said potential source to the base electrode of said second transistor to control the discharge of said capacitive means.

6. The pulse generator set forth in claim 5 including means in said second circuit means for controlling the parallel impedance provided by said second transistor.

7. The pulse generator set forth in claim 5 in which said first transistor includes an emitter electrode and in which a third circuit means including said contact means and said potential source are provided for controlling the potential supplied to said emitter electrode.

8. A signal generator comprising relay means including two pairs of contacts, a first pair of said contacts being normally open and a second pair of said contacts being normally closed; a first controlled conduction device having two control electrodes and an output electrode; means connecting said output electrode to said relay means to provide means for operating and releasing said relay means; capacitive means connected to one of said con trol electrodes; a potential source; means including said second pair of contacts for connecting said capacitive means to said potential source; a voltage dividing network connected to said potential source for supplying a biasing potential to the other control electrode of said first controlled conduction device; means including said second pair of contacts for controlling the potential supplied to said other control electrode by said voltage dividing network; a second controlled conduction device having a control electrode and being connected to said capacitive means; and means including said first pair of contacts for connecting said potential source to the control electrode of said second controlled conduction device.

References Cited by the Examiner UNITED STATES PATENTS 3,019,356 1/62 Teplot et a1. 307-132 MILTON O. I-IIRSHFIELD, Primary Examiner. 

1. A PULSE GENERATOR COMPRISING RELAY MEANS INCLUDING AN OPERATING WINDING AND TWO PAIRS OF CONTACTS, ONE OF SAID PAIRS OF CONTACTS BEING NORMALLY OPEN AND THE OTHER OF SAID PAIRS OF CONTACTS BEING NORMALLY CLOSED; A FIRST CONTROLLED CONDUCTION DEVICE HAVING A CONTROL ELECTRODE AND BEING CONNECTED TO SAID OPERATING WINDING TO CONTROL THE OPERATION OF SAID RELAY MENAS; CAPACITIVE MEANS CONNECTED TO SAID CONTROL ELECTRODE; A SECOND CONTROLLED CONDUCTION DEVICE CONNECTED TO SAID CAPACITIVE MEANS; A POTENTIAL SOURCE; AND CIRCUIT MEANS INCLUDING A FIRST PAIR OF SAID CONTACTS FOR CONNECTING SAID POTENTIAL SOURCE TO SAID CAPACITIVE MEANS TO CHARGE SAID CAPACITIVE MEANS SAID CIRCUIT MEANS ALSO INCLUDING A SECOND PAIR OF SAID CONTACTS FOR CONNECTING SAID POTENTIAL SOURCE TO SAID SECOND CONTROLLED CONDUCTION DEVICE TO CONTROL THE DISCHARGE OF SAID CAPACITIVE MEANS. 